Lamination and Sintering Shrinkage Behavior in Multilayered Ceramics

Abstract

Variations in lamination conditions, such as pressure, temperature, and time, changed the laminated density of multilayered alumina but had no effect on the sintered density. The present results showed that sintering shrinkage values differ with lamination conditions and vary inversely with laminated density. When lamination was accomplished using a press die, the difference in shrinkage between the X-Y and the Z directions was <1%. The effect of the press die could be explained by introducing a new factor, the SDF (shear deformation factor), which represents the ratio of area change in the X-Y direction before and after lamination. The lamination of green sheets exhibited almost the same behavior as did the compression of granules. A linear relationship also was found between laminated density and the logarithm of lamination pressure. Results for sintering shrinkage in the overall range of measured laminated densities showed that sintering shrinkage behavior could be divided into three regions; that is, the laminates had three packing structures with different laminated densities. A new factor (k), related to packing structure values before and after sintering, was introduced to explain the sintering shrinkage behavior. Each k value was obtained from the relationship between laminated density and sintering shrinkage. Comparing k factors for the laminated densities (X-Y and Z) under various lamination conditions made it possible to systematically analyze variations in the sintering shrinkage behavior of laminates with processing conditions. An estimation of sintering shrinkage was possible from that analysis.